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Arada [10]
3 years ago
7

Calculate the percent activity of the radioactive isotope strontium-89 remaining after 5 half-lives.

Chemistry
1 answer:
maria [59]3 years ago
5 0
The answer to this question would be: 3.125%

Half-life is the time needed for a radioactive molecule to decay half of its mass. In this case, the strontium-89 is already gone past 5 half lives. Then, the percentage of the mass left after 5 half-lives should be:
100%*(1/2^5)= 100%/32=3..125%
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3Fe+4H2O(yields) Fe3O4+4H2. What is the mole ratio of Fe3O4 to Fe?
WINSTONCH [101]

<u>Answer:</u> The correct answer is Option A.

<u>Explanation:</u>

Mole ratio is defined as the ratio between the stoichiometric coefficients of the molecules present in the chemical reaction.

For the given balanced chemical equation:

3Fe+4H_2O\rightarrow Fe_3O_4+4H_2

By Stoichiometry of the reaction:

3 moles of iron metal reacts with 4 moles of water to produce 1 mole of iron oxide and 4 moles of hydrogen gas.

The mole ratio of Fe_3O_4:Fe=1:3

Hence, the correct answer is Option A.

7 0
3 years ago
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Which pair of elements form an ionic bond with each other?
kherson [118]
1) KCl 
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3 years ago
a beaker of benzene is at room temperature. what is its vapor pressure. Is this vapor pressure large enough to cause the benzene
Serhud [2]

Answer:

(1). The vapor pressure is 91 mmHg at 20°C.

(2). No, benzene will not boil at sea level.

Explanation:

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The vapour pressure of benzene can be gotten from the table showing the vapor pressure of different liquids.

Boiling point can simply be defined as the point or the temperature in which the vapor pressure is the same with the atmospheric pressure.

The atmospheric pressure is 760mmHg, while the vapor pressure at sea level is at the temperature of 15°C which is equal to 71 mmHg( from the table showing the vapor pressure of different liquids).

71 mmHg is not equal to 760 mmHg, thus, at sea level Benzene will not boil.

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PLEASE HELP ASAP!!!!!!!!
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Answer:

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